The invention relates to a follower fall arrest device used with a fixed safety rope and comprising a body equipped with a securing system arranged to occupy either an active locking position in case of a fall or an inactive unlocking position enabling the user to progress along the rope in the ascending direction, or in the opposite direction when performing a controlled descent, said securing system comprising:                a support arm articulated on a first spindle of the body,        a locking roller in the form of a cylindrical wheel mounted rotating free on a second spindle securedly attached to the support arm,        and a centrifugal coupling means arranged between a drive member of the roller and the support arm so as to occupy a disengaged position or an engaged position.        
State of the Art
In normal use for ascending or descending, fall arrest devices follow the progression of the person along the rope without causing any jamming. The person is free to move without any manual unlocking action on the fall arrest device. Locking only takes place in case of a fall.
The securing system of known fall arrest devices generally comprises a pivoting lever having at one of the ends thereof an attachment ring for connection to a harness, and at the opposite end thereof a cam for jamming the rope. Such an arrangement acts as a jamming cleat, which is liable to prevent locking if the user were to grab the lever in case of a fall.
The document WO 00/24471 relates to a two-directional locking device for a fall arrest device, comprising a locking means equipped with two cams actuated in independent manner by a common locking member in reaction to a sudden change of weight. Locking of each of the cams depends on the incline of the rope with respect to the frame of the means.
The document U.S. Pat. No. 4,923,037 describes a fall arrest device having a securing system composed of an articulated support arm which is equipped with a cylindrical wheel mounted rotating free, and with a centrifugal mechanical coupling means arranged as a pawl. The circumference of the wheel comprises a series of teeth forming a sprocket causing rotation of the wheel by friction effect with the rope. To insert the vertical lifeline in the fall arrest device, an articulated U-shaped angle bracket has to be used and the latter be made pivot outwards, which complicates operations. The use of springs in the form of pins does not enable the locking threshold of the coupling means to be controlled with precision.